function show_error(xhr){

	var iWidth=800; 
	var iHeight=600; 
	var iTop = (window.screen.availHeight-30-iHeight)/2; 
	var iLeft = (window.screen.availWidth-10-iWidth)/2; 
        window.open('','','top='+iTop+',iLeft='+iLeft+',width='+iWidth+',height='+iHeight
           +'toolbar=no, scrollbars=yes,menubar=no,location=no, resizable=yes').document.write(xhr.responseText);
       

}